Some protists, like these
Paramecium
, act much like animals. Notice the tiny hair-like cilia that help them move. The food vacuoles, where they digest their prey, are colored in orange.

Animal-like Protists

Animal-like protists are called protozoa.
Protozoa
are single-celled eukaryotes that share some traits with animals. Like animals, they can move, and they are
heterotrophs
. That means they eat things outside of themselves instead of producing their own food.

Animal-like protists are very small, measuring only about 0.01–0.5mm. Animal-like protists include the flagellates, ciliates, and the sporozoans.

Different Kinds of Animal-like Protists

There are many different types of animal-like protists. They are different because they move in different ways.

Flagellates
have long flagella, or tails. Flagella rotate in a propeller-like fashion, pushing the protist through its environment (
Figure
below
). An example of a flagellate is
Trypanosoma
, which causes African sleeping sickness.

Other protists have what are called transient
pseudopodia
, which are like temporary feet. The cell surface extends out to form feet-like structures that propel the cell forward. An example of a protist with pseudopodia is the amoeba.

The
ciliates
are protists that move by using cilia.
Cilia
are thin, very small tail-like projections that extend outward from the cell body. Cilia beat back and forth, moving the protist along.
Paramecium
has cilia that propel it.

The
sporozoans
are protists that produce spores, such as the
toxoplasma
. These protists do not move at all. The spores develop into new protists.